Sewing-machine thread cutter



April 1 1952 F. H. Loomis SEWING MACHINE THREAD CUTTER Filed June I5, 1950 Patented Apr. 1, 1952 UNITED vSTATES PATENT OFFICE 'f;

SEWING-MACHINE THREAD CUTTER Fred H. Loomis, Woodhaven, N. Y.

Application June 3, 1950, Serial No. 165,952

Claims.

This invention relates to a sewing machine thread cutter. More particularly, the invention relates to chain stitch machines of every description, and especially to those used in the lglove making industry.

It is a common practice in the glove making industry to cut the thread by h-and and then to trim it to appropriate length. The thread may either be torn apart or severed by means of a pair of scissors or other suitable cutting means. The

thread trimming operation generally calls for the use of a pair of scissors or a sharp lol-ade or the like. These two operations are time consuming and costly.

ingly. A sufficient length of thread is allowed to compensate for the pulling of the thread following the cutting operation. Nonetheless, the thread is cut so short that there is no need for a thread trimming operation to trim the thread for finishing purposes.

The thread cutting mechanism herein described and claimed comprises two separate but cooperating elements: the first is a thread measuring member, the second is the thread cutter proper. The thread measuring member is adjustable to measure off and feed different lengths of thread. The thread cutter performs two functions: in the first place, it pulls off a measured length of thread; in the second place, it cuts or severs the thread. It is the measuring device which determines the extent to which the thread .cutter will pull the thread before severing it.

The invention may assume two `preferred forms, among others. The measuring device may be identical in both cases. The cutter will, however, differ in the two cases. In the one case,

y the cutter will move in an arcuate path into the loop of thread. The leading end of the cutter will be somewhat wedge-shaped and dull and it will tend to open up the loop to the extent allowed `by the measuring device. Behind the dull point g is a sharp edge which constitutes the cutter proper and when this sharp edge yengages the thread it severs the same In the second case, the cutter travels a straight path into the loop of the thread. It too is provided with a relatively dull, wedge-shaped leading end which spreads the loop to the extent that ther measuring device will permit. Unlike the first mentioned cutter, the wedge-shaped point of the second mentioned cutter has the shape of a modied arrow head. When the cutter enters the loop, its diagonal leading edge cams or wedges the loop to larger proportions. The cutting ac'- tion takes place only after the arrow-shaped head passes completely through the loop on its forward movement and then begins to Vmove backwardly to its original, inoperative posi-tion. The back edge of the arrow head is .thereby brought into engagement with the thread and the cutting or severing operation then takes place. The back edge is the cutting or severing edge.

The two preferred forms of the invention above mentioned are illustrated in the accompanying drawing in which:

Fig. 1 is a view of -a two needle, three thread chain stitch machine, showing the thread measuring device and the arcuate thread cutter installed thereon.

Fig. 2 is an enlarged, fragmentary view of said arcuate thread cutter and of the adjacent. parts of the machine, looking upwardly in the direction of arrows 2, 2 of Fig. 1. Fig. 3 is a similar view showing the position Vof the cutter immediately following the thread cutting operation. i

Fig. 4 is a view showing the measuring device and looking in the direction of arrows I, 4 of Fig. l.

Fig. 5 is an enlarged view, partly broken away and in section showing the thread measuring device in its raised or elevated position.

,ingit in process of entering the loops of thread.

Fig. 10 is a similar view showing `the arrow heads of the cutter after they have passed completely through the loops.

Fig. 11 shows the same cutter after it has moved backwardly and after it has severed the thread.

The dotted lines 20 in Fig. 1 illustrate a typical two needle, three thread chain stitch machine frequently used in the glove making industry. When the foot lifter 2l is in elevated position, the presser foot 22 is in its lower, operative position, and when the foot lifter is in lowered position, the presser foot is in elevated position. The thread 23 feeds from spools of thread in conventional manner and it passes through the ma- Vject is to sever these loops to the right length lso as to avoid a subsequent thread trimming operation and also to place the machine in proper condition to receive additional work.

The thread cutter proper 30 comprises a hooks'haped blade El, a handle 32 supporting said blade and by which the blade is actuated, a screw 33 `or otherV suitable fastening member by which the handle is pivotally mounted on the underside of plate 25, and a torsion spring 34 which acts upon the handle to urge the blade into inoperatve Yposition as shown in Fig. 2.l The torsion spring is coiled around screw 33, and one end of it engages the handle Vand the opposite end engages a pin 35 which anchors said last mentioned end of the spring to plate 25. Y

When the handle of theV cutter is turned in clockwise direction as viewed in Fig. 2, its hookshaped blade 3l will enter loops 21 and sever them as shown in Fig. 3. It will be noted, that the hook-shaped blade tapers backwardly from a pointed end to a somewhat wider shank. Stated differently, the blade is wedge-shaped to enable it to spread the loops to enlarged proportions when it enters `the loops. This has the effect of pullngthe thread to proper length before theV loops are severed. To insureV against premature cutting of the thread before the loops are enlarged to proper proportions, the blade lis provided with a vrelatively dull Ycutting edge immediately Ybehind its pointed tip. In other words,

' the cutting edge of the blade is sharpened a spaced distance from the pointed tip of the blade to avoid a cutting action upon the thread until the blade has thrust its way into the loops a sufficient distance to enlarge them to proper proportions.

The cutter 40 shown in Figs.V '9, 10 Vand 11 is based on the same principle of wedging or camming the loops of thread'to enlarged'proportions.

VIt comprises a pair of blades 4l and 42 respectively, a shank43 supporting said blades, a pair 34 acts upon handle'32. There is a slot 49 formed in the handle and a pin 50 on the shank of the cutter which engages said slot. Hence when handle 46 is turned on pivot 41, it causes the cutter to move longitudinally of itself along its supporting brackets 44 and 45. Turning the handle in one direction will thrust the cutter forwardly and turning it in the opposite direction will retract the cutter.

It will be noted that blades 4l and 42 are spaced from each other along their full length. Each blade has a barb or arrow shaped head 53 which serves as a wedge for loop enlarging purposes. When handle 46 is turned in clockwise direction, as viewedrin the drawing, wedge-shaped heads 53 of the two blades are caused to enter the two loops of thread'55. See Fig. 9. Fig. 10 shows heads 53 of the two blades after having passed completely through the loops of thread. Handle 46 may now be turned in counter-clockwise direction to retract the two blades and return them to their original, inoperative position. The back edges 53a of the two wedge-shaped heads 53 now serve as the cutting edges of the blades andV they engage the loops to sever them in the manner shown in Fig. ll. These cutting edges 53a may or may not 'be sharp, depending uponY whether it is desired to out or tear the thread. Thus the wedge-shaped heads of the blades may be used in the first instance to widen the loops'and thereby to pull the thread to appropriate length. If it be desired to further pull upon the thread for Y the same purpose, the cutting edges of the blades of angle bars 44 and 45 respectively which form .a channel between them and which support the are rendered sufciently .dull vto avoid cutting the thread until after said cutting edges pull p the thread to a predetermined extent, over and above the initial pull of the wedge-shaped heads of the blade.

Although hook-shaped blade 3| provides a somewhat different appearance from that of barb-shaped blades 4l and 42, in principle these blades are alike. They are all wedge-shaped with leading pointed ends or tips. They are' thereby enabled to enter the loops of thread and wedge them to enlarged proportions. In the case of blade 3l, one blade alone enters and enlarges two loops of thread. In the case of blades 4I and 42, each blade acts upon only one loop .of thread. Another difference between blade, 3| and blades 4l and 42 resides in their respective directions of movement during the performance of the wedging and cutting operations. Blade 3l moves forwardly both to wedge and to cut. Blades 4I and 42 move forwardly to wedge and backwardly to cut. If desired, diagonal edges 53h of the wedgeshaped heads of blades 4l and 42 may be sharpened a spaced distance from the pointed tips of said wedge-shaped heads, to serve as the. cutting edges of said blades. With such modification, blades 4! and 42 would wedge and cut when moving forwardly.V Y

The measuring ldevice G0 Vshown in Figsfl, 5 and 6 controls the extent to which the Wedgeshaped blades are allowed to pull upon the thread. This measuring device comprises a vertically slidable weight 6 l, a bracket 62 which carries-said weight, and an adjusting member 63. Bracket 62 has a vertical channel 64 YformedV therein. Weight 6| is U-shaped in horizontal section and its yoke is disposed in said vertical channel.V VThe arms or legs of the U-shaped weight project backwardly to embraceV bracket 62 yand Vthereby to prevent the weight from falling out of channel 64. The weight is free to move both upwardly and downwardly but screw adjustment member 63 serves as a stop to limit its downward movement. The screw adjustment member may be locked in any selected position on bracket 62 to limit the downward movement of the .weight Holes 65 are formed in bracket 62 and corresponding holes 66 are formed in weight 60. Holes 65 and 66 are in registration with each other and there are as many groups of registering holes as there are threads 23. It will be seen that these holes are adapted to receive said threads and they serve as eyes for said threads. Behind bracket 62 is an anvil or block 'l0 and fastened to said block or anvil is a plate 'H having holes 'I2 formed therein in registration with holes 65 and 66. Holes 12 also serve as eyes for the thread and it will be understood that the thread feeds from a spool or spools (not shown) to and through eyes 12, across block 10, and then through eyes 65, 66 and 65. The thread then engages the usual tensioning devices such as tensioning devices 15 and 16. and eventually it leads into needles 11 and 18, as well as into and through the loopers. Mounted on foot lifter 2l is a clamping member 'I9 which is situated for co-action with anvil 10. When the foot lifter is brought downwardly to elevate the foot, clamping member 19 is thereby swung into clamping engagement with anvil 10. The thread is thereby caught between clamping member 19 and the anvil and further feeding of the thread from the spool or spools is thereby prevented.

The following is the action of the weight and its relation to the thread clamp and the thread cutter. When the foot lifter is in elevated position, the presser foot is in lowered, operative position. and the sewing operation takes place. Thread is fed from the spools through the eyes of the clamping member, the weight and the weight supporting bracket, through the tensioning devices of the machine and thence through the needles, work and loopers. At the conclusion of a given stitching operation, the foot lifter is lowered and the presser foot is moved into elevated position. The clamping device now clamps the thread and prevents further feeding of the thread from the spools. The cutting attachment may now be actuated and the blade or blades of the cutting attachment enters or enter the loops of thread. These loops are thereby caused to spread out and the thread is thereby pulled in the same direction in which it is normally fed, to render such enlargement of the loops possible. Since the clamping device prevents pulling of the thread from the spools, the only source of thread for the pulling operation is the weight itself. It will be understood that the weight normally hangs from the thread and its weight is sufficient to enable it to pull down upon the thread, and to rest upon the screw adjustment member in the manner shown in Fig. 1. When the cutter enters and enlarges the loops of thread, the thread is pulled taut and the weight is thereby raised to its elevated position shown in Fig. 5. It will thereby be seen that the screw adjustment member which limits the downward movement of the weight will, by the same token, determine the iii) extent of upward movement of the weight when the cutter enters the loops and thereby pulls the thread taut.

The foregoing is descriptive of preferred forms of this invention and it will be understood that these forms may be modified in many ways and other forms provided, all within the broad scope and spirit of this invention.

I claim:

l. In combination, a chain stitch sewing machine, a thread cutter mounted under the worksupporting plate of said sewing machine for severing the loops of thread formed by said sewing machine in the normal course of its stitching operations, a thread clamping member mounted on said sewing machine for clamping the thread during the thread cutting operation, and a thread measuring and feeding member mounted on said sewing machine and engaging the thread between the thread clamping member and the thread cutter.

2. The combination of claim 1, wherein the thread cutter is wedge-shaped and is movable into the loops of thread to enlarge said loops of thread and thereby to pull the thread from the thread measuring and feeding member.

3. The combination of claim 1, wherein the thread measuring and feeding member comprises a weight which hangs on a horizontal stretch of thread and which is vertically movable within a predetermined range of movement.

4. The combination of claim 1, wherein the thread cutter is wedge-shaped and hook-shaped and provided with a cutting edge a spaced distance behind its leading end, said thread cutter being movable into the loops of thread to enlarge said loops and thereby to pull the thread from the thread measuring and feeding member before its cutting edge engages and cuts the thread.

5. The combination of claim 1, wherein the thread cutter is provided with a bifurcated wedgeshaped blade forming a pair of spaced blade portions, each of which is substantially barb-shaped with a cutting edge a spaced distance behind its leading end, said barb-shaped blade portions being movable into loops of thread to enlarge said loops and thereby to pull the thread from the thread measuring and feeding member before their cutting edges engage and cut the thread.

FRED H. LOOMIS.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,193,906 Lindner Aug. 8, 1916 1,319,668 Morris Oct. 21, 1919 1,401,465 De Voe Dec. 27, 1921 1,902,864 Klenschmit Mar. 28, 1933 2,358,731 Olson Sept. 19, 1944 FOREIGN PATENTS Number Country lDate 112,817 Sweden Oct. 26, 1944 

